Brushing, flossing, and gargling may all be part of your daily oral hygiene routine, but taking these steps may not be enough if you have other issues.
Medications like antidepressants, diuretics, and aspirin can dry the mouth. With dry mouth, there is a lack of saliva, and saliva is what rinses away bacteria that make breath odor foul.
Bacteria – Some people may be prone to bad breath more than others. Bacteria exist on the tongue, and expel gases as they munch on food particles and other substances broken down from saliva. Also, they multiply at night, since the salivary glands slow down when you are sleeping. H. pylori, a type of bacteria that can cause stomach ulcers, can cause bad breath and gum disease if it finds a place to reside in your mouth.
Respiratory tract infections- While gum and tooth infections can cause bad breath, so can bronchitis, sinusitis, and even colds. RTIs break down tissue, which starts a flow of mucus and cells that feed bacteria that can emit foul odors.
Skipping breakfast– Not only does breakfast benefit your body and mind, but it helps to stimulate saliva production and scrub bacteria from the tongue (depending in what you eat, of course).
Diet- Low-carb diets can burn stored fat, thus creating toxic-smelling ketones. Foods that generate large amounts of amino acids, like dairy products and foods high in protein, can fuel the bacteria that produce bad breath. Obesity has also been linked with bad breath.
Breathing out of your mouth- When the tissues in your mouth are dry, saliva is prevented from washing away bacteria; thus, bad breath is encouraged. Major candidates for this are people who suffer from sleep apnea, asthma, and snoring.
Chronic illnesses- Breath that is chronically potent in a certain smell can signify a disease. For example, kidney failure can make your breath smell fishy, and uncontrolled diabetes can make your breath smell fruity.
Alcohol- Plain and simple, alcohol is dehydrating, and having a dry mouth encourages bad breath.